Amp capacitor

[Guest]

needing to buy a capacitor atm

Hedlights are dimming when sounds cranked up

Car is running two amps both rated at 800w

Just want to know what capacitor(s) you are running and what size ie how many Farrad

And what brands you recommend

Cheers Rick

[Joker]

.1 farad for every 100 watts was the forumlae?

[subout]

wouldnt waste your money on a cap, just upgrade battery, used to run over 6000WRMS (real rms) in the spl car with no cap

[Guest]

 subout said:

wouldnt waste your money on a cap, just upgrade battery

To what?

battery is a near new calcium one (X55D23C)

[subout]

 Ichi Ban']

[quote name='subout said:

wouldnt waste your money on a cap, just upgrade battery

/quote]

To what?

battery is a near new calcium one (X55D23C)

i was running a yellow top optima D34 had 750 CCA, used plenty of times for burps with never any issues

[Guest]

so a gel cell battery then - will go get one

Thanks

[Scoobydoo]

Yep I concur... a capacitor is just a band aid really, for the bigger problem. A good gel-cell battery will solve all issues

[spark_38]

I was using an Exide Orbital 750CCA, 3 amps, 1600W RMS total, had no issues with lights dimming, or car starting with it blasting for over 2 hours!!

And I could leave the car parked up for over 3 weeks while away on holiday.

[Joker]

summ it up a $300 Battery or a 1.6~ Farad cap?

http://www.trademe.co.nz/motors/car-stereos/other/auction-388012107.htm

for $10

[Scoobydoo]

A very good purchase for a car (if lights are dimming then it's signs the battery isn't in very good condition anyway)

vs

A smelly pile of poo

[legacy666]

I run a 1 farad Monster Cap. Ive had it since my spl days(years ago),no fancy display. You simply run your positive across the caps+ and earth the caps- helps the juice get to my alpine 4 channel and my precision power 2 channel,sub,6x9s,6inch components. Without it my lights would dip, with it theres no issues.

http://shop.ebay.com/i.html?_from=R40&_trksid=p5197.m570.l1311&_nkw=1+farad+capacitor&_sacat=See-All-Categories

http://www.trademe.co.nz/motors/car-stereos/other/auction-386961470.htm

$69 for a 2 farad. do it, go on.

[Scoobydoo]

 legacy666 said:

I run a 1 farad Monster Cap. Ive had it since my spl days(years ago),no fancy display. You simply run your positive across the caps+ and earth the caps- helps the juice get to my alpine 4 channel and my precision power 2 channel,sub,6x9s,6inch components. Without it my lights would dip, with it theres no issues.

http://shop.ebay.com/i.html?_from=R40&_trksid=p5197.m570.l1311&_nkw=1+farad+capacitor&_sacat=See-All-Categories

http://www.trademe.co.nz/motors/car-stereos/other/auction-386961470.htm

$69 for a 2 farad. do it, go on.

I still stand by my previous comments.

[subout]

 Scoobydoo said:

A very good purchase for a car (if lights are dimming then it's signs the battery isn't in very good condition anyway)

vs

A smelly pile of poo

agreed, cracks me up how people think caps are a fix. Its like putting a bandaid on something that needs stitches

[spark_38]

In my 8 or so years of car audio; I've never used a cap. Even when I had a sub-standard battery. Good clean grounding is proven to be more effective, up the stock ones to at least 4 gauge - run a distro block and put several more grounds on the engine block and surrounding metal chassis'

[legacy666]

 subout']

[quote name='Scoobydoo said:

A very good purchase for a car (if lights are dimming then it's signs the battery isn't in very good condition anyway)

vs

A smelly pile of poo

/quote]

agreed, cracks me up how people think caps are a fix. Its like putting a bandaid on something that needs stitches

or putting a cast on something that needs a bandaid. A $300 cast.Just saying with gas at over $2/l I'd rather put my $300 into my tank, when a cheaper cap(which is designed to keep a constant voltage) will do the job.just my opinion.

As mentioned good wiring and earths help alot

[boon]

A 1 farad cap stores less energy than a 9v battery. Just gonna throw that out there.

There's a lot of reasons why your lights dim with high power audio... I wrote up a huge thing about why even a battery won't solve your problems (theoretically a cap is better, although relatively useless on a big system if they're less than ~10F)

Mostly it comes down to the fact that you've only got about 50A on tap at 14.4v from your alternator, after that you're getting 12.8v or so from your battery. Go crank your sounds with the engine off, I bet you a dollar they won't dim unless you're running a pretty rude amount of power.

The reason a gel or AGM battery works a little better is because when they're freshly charged they float at close to 14v...

EDIT: Stuff it, let's go into some theory here:

1 Farad means that it can supply 1A at 1A for 1 second

C = It/V, or Capacitance = Current x Time divided by voltage

So we have 1 Farad and about 14v so with some quick re-arranging

14 = Current x time

So you can pull 14A for 1 second before the cap is discharged. At 14v this makes ~196w input, if we factor in a Class A/B amp and its roughly 65% efficiency you get 128w of output for 1 second from your cap.

Now this is all wonderful if you're powering your amp with nothing but a cap but the problem is that the cap won't discharge below the overall voltage of the system. So once your alternator can't keep up, let's say you're dropping to 12v.

You get a 2v discharge from the cap, throw that into the earlier equations and you get 18.2w for 1 second. And once the cap discharges to the same voltage as the rest of the system, it does NOTHING except present an additional load on your alternator, because it is trying to charge up again.

To bring this all back around though. Music is transient load, your voltage drop may in fact only last 0.1s. In which case the cap can discharge 182w for that 0.1s, and prevent your headlights from dimming! Oh happy days

In conclusion, they do, in fact, do what they're advertised to on a small system. They also help to mitigate voltage drop across your power cable.

[spark_38]

Or in basic english:

Car off = power from battery

Car on = power from alternator

And most decent batteries, you'll be able to get a more than 50-80A from them - is that why SPL comps run with the car off?

[boon]

 spark_38 said:

Or in basic english:

Car off = power from battery

Car on = power from alternator

And most decent batteries, you'll be able to get a more than 50-80A from them - is that why SPL comps run with the car off?

Eeer, kinda... in lower classes it's car off, in higher classes it's engine optional but you're limited to a certain number of RPM... so you just run 4 300A alternators anyway.

A good battery will provide ~800A, Gel batteries usually good for close to 1000A at a burst... and some of the AGM rapid discharge batteries I have kicking around are good for like 1550 CCA or ~3000A discharge. Which is handy when your amps pull 1000A

[WRXONP]

i ran 2x 1200w class d amps with out capacitors on a 600cca and on long bass notes the lights would dim . . not on short booms though . . fitted 2x 1 farad caps and problem solved . . . was a Non turbo car and you could really feel the power getting weaker when driving with full bass . . . caps fixed it

[DRFVDR]

Just run another battery near the amp

[subieboy]

Yep i concur with Gel cel battery

I have a 1.5 Farad cap for the bling effect...